81 Flutter interview questions with answers

All Flutter interview questions

• What is the difference between `var`, `dynamic`, and `final` in Dart?

• What is null safety in Dart and why does it matter?

• What is the null assertion operator (`!`) and when should you use it?

• What are null-aware operators in Dart? Name three examples.

• Explain the difference between a `List`, `Set`, and `Map` in Dart.

• What is a `Future` in Dart and how is it different from a `Stream`?

• What is the `async`/`await` syntax in Dart?

• What is type promotion in Dart?

• What are named and positional parameters in Dart functions?

• What is a closure in Dart?

• What is the difference between `extends`, `implements`, and `with` (mixin) in Dart?

• What is the difference between `StatelessWidget` and `StatefulWidget`?

• What is `BuildContext` and why is it important?

• Explain the widget tree, element tree, and render tree in Flutter.

• What is the purpose of widget `Key`s and when should you use them?

• What is the difference between `ValueKey`, `ObjectKey`, and `UniqueKey`?

• What is `const` constructor and why is it important for Flutter performance?

• Explain the Flutter layout system: how do `Column`, `Row`, `Expanded`, and `Flexible` work?

• What is `setState()` and why does calling it trigger a rebuild?

• What is the lifecycle of a `StatefulWidget`? List the key methods.

• Why is `dispose()` important and what should you clean up there?

• What's the purpose of `RepaintBoundary` and when should you use it?

• What is state management and why is it important?

• What are the problems with using `setState()` for complex apps?

• What is the Provider pattern and how does it work?

• What is Riverpod and how is it different from Provider?

• Explain the BLoC pattern and why interviewers ask about it.

• Compare Provider, Riverpod, and BLoC: when would you use each?

• What is `ChangeNotifier` and when do you use it?

• What is `Selector` in Provider and why use it instead of `Consumer`?

• What is `GetIt` and how does it relate to state management?

• How do you test state management code (Provider/Riverpod/BLoC)?

• What is the difference between the old `Navigator` (v1) and modern routing approaches?

• What is GoRouter and what problems does it solve?

• How do you pass data between screens in Flutter?

• What is deep linking and how does GoRouter support it?

• How do you handle navigation state with GoRouter?

• What is `ShellRoute` in GoRouter and when do you use it?

• How do you implement authentication guards with GoRouter?

• What problems occur with Navigator 1.0 named routes at scale?

• What is clean architecture and why is it important for large apps?

• What is the repository pattern and how does it work?

• What is dependency injection and how do you implement it in Flutter?

• Explain the difference between singleton and factory patterns in Flutter.

• What is MVVM architecture in Flutter and how does it differ from MVC?

• What is the use-case layer in clean architecture and why include it?

• How do you structure folders/packages in a clean architecture Flutter app?

• What is the difference between entity and model in Flutter architecture?

• What are isolates in Dart and when do you use them?

• What are platform channels and when do you use them?

• How do you handle errors and exceptions in async Dart code?

• What is `Future.wait()` and when do you use it?

• How do you profile and optimize Flutter app performance?

• What is the difference between `ListView.builder` and `ListView` for long lists?

• How do you implement CI/CD for Flutter apps?

• What are the differences between debug, profile, and release builds in Flutter?

• How do you test Flutter apps? What's the difference between unit, widget, and integration tests?

• What is `WidgetsFlutterBinding` and when do you use it?

• What are Records in Dart and how do they enable multi-value returns?

• How does pattern matching work in Dart 3? Give a practical example.

• How does a switch expression differ from a switch statement in Dart, and when should you use it?

• What do class modifiers (`base`, `interface`, `final`) do in Dart 3?

• What is a sealed class in Dart and why is it more useful than an abstract class in some cases?

• What is Impeller and why did Flutter switch to it as the default rendering engine?

• How does WebAssembly (WASM) improve Flutter Web performance?

• What is tree-shaking in Flutter release builds and why does it reduce app size?

• What are Signals in Flutter and when should you use them over Riverpod?

• How does Riverpod (2.x+) differ from Provider in terms of memory efficiency and type safety?

• When should you choose BLoC over Riverpod for state management?

• How do you implement offline persistence with Riverpod?

• What are the key differences between building Flutter Web vs traditional web frameworks?

• What are the platform-specific considerations for Flutter Desktop (Windows/macOS)?

• How does Dio differ from the default `http` package and when should you use it?

• How do you integrate Firebase Authentication in Flutter and what are common pitfalls?

• What is Shorebird code push and when should you use it instead of App Store/Play Store updates?

• What is `InheritedWidget` and how does it pass state down the widget tree? (the foundation of Provider)

• Contrast `StreamBuilder` and `FutureBuilder`. When do you use each?

• What is the `Hero` widget and how does shared-element animation work across screens?

• What is `MediaQuery` and how do you use it to build responsive/adaptive layouts?

• Contrast implicit and explicit animations in Flutter (`AnimationController` + `Tween`).

• What is `GestureDetector` and how does the "gesture arena" resolve gesture conflicts?